Lung cancer is the leading cause of cancer death in the US. Metastatic non-small cell lung cancer (NSCLC), an incurable disease, accounts for the vast majority of these deaths. Chemotherapy may prolong life by a matter months and may relieve symptoms in some, but is toxic and expensive. Therefore, best supportive care (BSC) that does not involve cytotoxic chemotherapy is considered a reasonable alternative. Preferences regarding tradeoffs between the potential benefits of chemotherapy for NSCLC and its toxicity are not well understood. Furthermore, it is unclear whether these benefits are sufficient to justify the economic costs to society. We propose to address these questions by performing a state-of-the-art cost-effectiveness analysis (CEA) comparing chemotherapy with BSC as the initial treatment strategy for NSCLS. Development and evaluation of innovative yet user- friendly methods to estimate each of the components of the cost- effectiveness ratio will be stressed. The proposed study will proceed in four steps. First, we will estimate the incremental survival benefit associated with chemotherapy using the results of a meta-analysis of randomized controlled trials and population-based tumor registry data. Second, we will collect primary utility and health-related quality of life (HRQL) data from patients and calculate the incremental quality-adjusted life years resulting from chemotherapy. Third, we will combine data from three sources - hospital cost data on a cohort of patients treated at the Dana-Farber Cancer Institute and Brigham and women~s Hospital, surveys on time and out-of-pocket costs among those same patients, and National Health Care Finance Administration claims data linked with SEER clinical data -- to estimate the incremental cost of chemotherapy. Finally, we will combine these data to perform a CEA of chemotherapy versus BSC in NSCLC, with particular attention to how the cost-effectiveness results vary with different perspectives on costs and preferences for health outcomes. This study would represent the first comprehensive attempt to calculate the cost-effectiveness of chemotherapy versus BSC for NSCLC patients. The research will help identify the most effective treatment strategies, taking into account not just survival, but also HRQL. The findings will guide policy makers and payers in making clinical and resource allocation decisions. And by developing new methodologic techniques, the research will lead to more efficient and valid CEAs of a wide array of Medical interventions.